xiv INTRODUCTION 



Disease," from a field observer's point of view, had been ascertained. Even at this 

 date the Committee were of opinion that they had discovered the principal causes 

 of mortality amongst Grouse ; but until they had further confirmed their suspicions 

 they decided not to publish anything in the nature of results. It was at this 

 stage that an impatient public and the necessity to stimulate dilatory subscribers 

 forced upon the Committee the necessity of publishing some account of their 

 progress, and the Interim Report issued in August 1908 was the outcome of 

 this demand. The Interim Report contained an account of the work done by 

 the Committee up to date, but omitted all reference to the results which had 

 only been achieved in part. 



During the second or research stage of the investigation the following special 

 points were studied: (1) The life history of the Trichostrongylus pergracilis, 

 which the Committee believed to.be the immediate cause of " Grouse Disease "; 

 (2) The life history of the other internal parasites of Grouse ; (3) The protozoal 

 parasites infecting the alimentary tract and blood of Grouse ; (4) The bacteriology 

 of Grouse ; (5) The various insects found on the moors both from the point of 

 view of insect-borne disease and from the point of view of food ; (6) The questions 

 affecting the food supply of Grouse, including the management of heather land, causes 

 of destruction of heather, e.g., frost, heather-beetle, etc. 



These lines of research were diligently followed up by the members of the 

 Committee's Scientific Staff during the last three years of the Inquiry the work 

 entailed long series of experiments carried out upon the open moor, in the labora- 

 tory, or at the Frimley observation area. The results have been unexpectedly 

 conclusive, considering the short time available for so great a task. 



The Committee consider that although their immediate object has been achieved, 

 viz., the elucidation of the causes of "Grouse Disease," the present Inquiry has 

 scarcely crossed the threshold of the investigation into the general pathology of 

 birds, and there is still a large amount of work which might be profitably under- 

 taken. The most important department of the research, so far at least as relates 

 to mortality amongst adult Grouse, was the investigation of the life history of 

 the strongyle threadworm. The work was rendered difficult owing to the small 

 size of this parasite, but thanks to the efforts of Dr Wilson, Dr Shipley, and 

 Dr Leiper, we are now in a position to speak with something approaching 

 certainty on the subject. These gentlemen have worked at the subject for 

 more than three years, and have not only ascertained the life cycle through which 

 this worm passes, but have discovered the conditions which are favourable or preju- 



